The fourth Iris was built in 1885 by A. Leslie & Co., Newcastle, England, and was purchased by the Navy from Miami Steamship Co. 25 May 1898 for service in the Spanish American War. However, reconditioning and conversion to a distilling ship was not completed until after the end of active operations against Spain. Iris commissioned at Norfolk Navy Yard 1 August 1898, Lt. Arthur B. Connor in command.

The distilling ship departed Norfolk 31 August and arrived Montauk Point, N.Y., 5 September. She departed New York Harbor 14 October for the Philippine Islands arriving Manila 18 March 1899. She acted as a general utility ship for the Asiatic Squadron in the Philippines during the occupation of the islands and during the subsequent insurrection. She decommissioned for repairs at Hong Kong 31 January 1900 and resumed duty in May.

Iris sailed for home in the fall of 1903 arriving San Francisco 13 November and decommissioning at Mare Island Navy Yard 18 December. She was overhauled there and placed in service as a collier for the Asiatic Squadron. For the next 5 years, she fueled United States vessels in the Orient.

She departed Manila 20 May 1909 for San Francisco where she was converted to a torpedo boat tender. She was placed out of service 15 October and recommissioned the same day. During the following years she served as parent ship for the Pacific Torpedo Fleet operating off the West Coast of the United States.

In the fall of 1915 disorder in Mexico threatened American citizens and interests. Iris arrived Topolobampo, Mexico 9 December to begin patrol duty on the Mexican coast. She remained in the area ready to act in the event of any emergency until departing La Paz, Mexico, 30 January 1916. She arrived San Diego, Calif., 4 February and began duty towing targets off southern California.

Two months later Iris was ordered to San Francisco. After arriving 16 April, she decommissioned at Mare Island 2 May 1916. Iris was transferred to the USSB 3 May 1917.